Conventional rectifiers for alternators known in the art have diodes that are secured to the surface of a heat sink by soldering or brazing. When an alternating current goes through the diodes, heat generated by the diodes may not be well distributed through the heat sink because the diodes are only attached to the heat sink with small contact areas. Therefore, heat may be dissipated insufficiently and result in damage of the rectifier.
In the conventional rectifier, the anode or cathode of a diode is typically secured to the heat sink by soldering or brazing. The attachment between the heat sink and a diode is only accomplished by one small attaching end. After a long period of vibration or a huge unexpected shake, the attachment may be loose or even totally disconnected. In addition, the diode is usually attached on an external surface that is susceptible to water infiltration.
A known technique using press-fit diodes has been adopted to overcome the drawbacks just mentioned above. As in FIG. 8, the metal case 53 is used to package the die 52 with the nail connector 51. The combinations are called press-fit diodes 5. Die 52 is completely embedded in the metal case 53 to avoid water infiltration and particle contamination. The press-fit diodes 5 are installed into the holes 21 and holes 31 from the bottom of the first sink plate 2 and the second sink plate 3. Because the press-fit diodes 5 are completely pressed into the holes 21 and 31, heat generated due to rectification can be well distributed around the first sink plate 2 and the second sink plate 3. And, the die 52 is completely secured. Therefore, the drawbacks described above can be overcome. However, there are still some shortcomings. The metal case 53 should be made by casting or lathing process. This makes the cost higher than before. The press-fit diodes 5 must be formed firstly before they are pressed into holes 21 and 31. This increases the labor cost. In addition, when press-fit diodes 5 are installed into holes 21 and 31, gaps exist between the metal case 53 and the sink plates 2 or 3. This will significantly reduce the heat dissipation efficiency.